Immediately prior to April 15th each year one sees a good number of tax cases being charged or plead. Clearly this can have the effect of deterring those who might be tempted to avoid paying taxes or perhaps not bothering to filing a tax return. For example:

A DOJ Press Release (Central District of California) reports that "the owner and operator of Newport Tux and Uniform in Newport Beach, California, pleaded guilty [ ] to evading the payment of his federal taxes." (see here -Download HannaPR.46.pdf ).

For a list of recent tax charges and convictions see TAXNEWS of the Tax Division of the Department of Justice.